Telemeter.



0. EPPENSTEIN.

TELEMETER.

ArPLlCATlON FILED OCT. 15. 1912.

Patented May14,1918.

ATES

OTTO EPPEN STEIN OF JENA, GERMANY, ASSIGNOR TO THE FIRM OF CARL ZEISS,0F

- JENA, GERMANY.

TELEMETER.

memes.

Specification oi Letters Patent.

Patented May 14, 1918.

Application filed Octoberlfi, 1912. Serial No. 725,785.

' specification.

The invention relates to that kind of telemeter, in which the ocularsystem lies between the objective lenses and the objective prism systemsraise the entrance openings above the head of the observer, eachobjective prism system being so formed, that the deflection in the planeof triangulation efiected by such system of a ray passing through it isnot influenced by small rotations, to which the whole objective prism Iations in the form of the latter are not transsystem is subjected in thesaid plane.

Up to the present only one telemeter of this kind has become known, viz.that one described in the French Patent Specification 425,511. In theinstrument there described each of the objective prism systems consistsof a pentagonal prism, in front of which two reflecting surfaces,parallel to each other, are disposed in such a manner as to displace theentering my so as to remain parallel to itself and in a directionperpendicular to the plane of triangulation. This dill combinationhowever deflects the axial ray four times and necessitates in additionto this a silvering of the two reflecting urfaces of the pentagonalprism.

According to the present invention the objective prism systems are soformed as to cause the axial ray to be deflected only three times ineach of them, without their losing the above explainednon-'sensitiveness to a rotation .inthe plane of triangulation. Anincidental advantage is, that at none of the reflecting surfaces theangle requisite for total reflection is exceeded, so that no silveringis necessary.

The employment of a prism system, which deflects the axial ray onlythree times and is non-sensitive in the above meaning of the term, asthe objective prism system of a telemeter is not new; it is knownthrough the English Patent Specification 3,172 of the year 1901. Theprism system is there formed by the cementing together ofaonce-reflecting and a twice-reflecting. prism, a difference in heightbetween the entering and the emerging ray corresponding to thedimensions of the prisms being obtained.

In the above mentioned English patent specification, by cementing theseparate prisms to each other or to a glass plate common to them, theunchangeableness in the relative position of the separate prisms issecured; the movin apart of the prisms, as in the telemeters, with whichthe present invention is concerned, renders it necessary, in order toinsure unchangeableness, to protect the constructional part, whichserves as carrier for the separate prisms, from alterations in its form.A convenient way of bringing this about is to rigidly fix the separateparts of each objective prism system to a tube (an inner tube) and tojournal this inner tube in another tube (an outer tube) yieldingly insuch a manner that alter- 'a sectional plan view of the telemeter alongline 7-7 of Fig. 5.

In Figs. 1 and 2 the objective prism system consists of the threereflecting prisms a a, a with simple reflecting surface, the contiguousprisms a and a of which system may also consist of one piece. In Figs. 3and 4 the system also consists of three simple reflecting prims a a athis system may be regarded as the same as that shown in Figs. 1 and 2,except that the rays pass through it in the opposite sense. I

If to the three deflections, which are effected by each of the prismsystems shown, he added an odd number of deflections throu h 90 in theplane of triangulation, cause by reflecting surfaces of the ocularsystem, standing perpendicular to the said plane, total erection of theimage results with each of the systems shown in Figs. 1

to 4. Erection only parallel to the direction of the base-line may beobtained, if one of the reflecting surfaces belonging to the ocutranceezie and. similarly tlirecte i er parallel encl oppositely directecl.

in Figs. 5 to 7 systems corresponding to Figs, 1 anti 2 are chosen forthe objective prism systems. The two contiguous priems of each systemconsist of one piste 07 are fixed rigidly each the bottom end ct aninner tube a, which cerries at its top end. the tiiircl prism a, Theinner tubes are universally iouizuaiecl eneli near its bottom end, icymeans of ring 03 in the outer tubes c, which are closeti at the top,and. are guicleel eacli near its top end, by means oi three rollers fcoaitially in these outer tubes. A glazed Window 9 serves for eachentrance opening. Theouter tubes 6 ere rigidly connected by ent vpiecesc with a tube it, in which the objective lenses '2 and the ocular k kare fixed. A giess Wedge Z, which can be displaced by means of the rackm and the pinion n by the small hand-Wheel 0, serves, on taking a range,for displacing the partial image derived from the Tiglit-i1ti1l end oithe base-line, The iiali erectecl scale a which is lined. tothe carrierr oi the Wedge, and the index 8 are visible through the Winclor-r 2f,'ilie left-hand axial ray is reflected,

includine' the reflection at the se aratino' C3 hi layer ct, in theseparating prism system at three simple reflecting surfaces of the prismM1, the right-hand axial ray suffers a reilection in the separatingprism system at the ridge surface of the prism ta in the imagefieici theartiel image comin from the lefthand en of the base-line is tl iereioretotally erect, that coming "from the right-hand encl invertecl in thedirection perpenuicular to the ease-lime.

I claim:

1. Horizontal telemeter with entrance opening at either end; comprisinge horizon pert containing two objective enses an 1 center @rism. systemlying between he eerie].

lens-es; oeular systein enc'i clevice and comprising further a verticalpart at either end of the horizontal part eitiier vertical partcontaining .eu objective nriera e stern eolapterl to tee said entranceopenings store the leeeti oi the olseerrer anti consisting oi? threeeiinple reflecting prlstirs 1 the ieg "gaetenuseeuriaces ct two oi whichprising; leein terpentiicuier to one Iolene perpendicunr to eech other,Wiiildiilt) third prism tieiiects the axial rey e gplene toer=oenciicular to saicl planeenei narallel to tne irection oi the axial rayentering the ob jective prism system 2. liiorizontai telemeter with anentrance opening at either end, comprising at horizon tal partcontaining trvo efiiectire lenses en ocular prism system lyingbBifiWEEil the eaiel lenses, en ocular system end a measuring tieviceand comprisin further at either end of the said; liorizontai part two"vertical tubes, an inner and. an outer one, each sueli inner tubeiieving the members of an objective prism system, rigidly tired to itsencls encl being yieldingly journaled Within and coaxisillv to the saidouter tuioes Wnicli latter tubes are themselves rigidly *mecl by theirbottom ends to the enris oi the said. horizon tal part, and tile saiclobjective prism eyetems being adapted to raise the said entranceonenings above the head of the observer anci consisting of three simplereflecting prisms, the hypotenuse-surfaces of two which prisms beingperpendicular to one plane and perpendicular to each other, While thethird prism deflects the axial ray in e plane perpendicular to saidplane end parallel to the direction oi the eniei my entering theobjective prism system,

@TT'O PPEFTEEN t1CHAliD Hares.

